"What you see in the logs is the filtered version.
Don't quote me here but I think we are going from the 8g setting to the 16g setting. That give you some idea how strong the high frequency vibration can be. And remember it is clipping before it…"

"We hope so. The vibrations of the frame are causing the accelerometers to saturate. This results in the average acceleration to go from -9.8 m/s to closer to 0. This makes the copter think it is falling and therefore it climbs.
We still get good…"

"Hi John,
It is hard to say too much about your tune without looking at the logs. I have developed autotune further for the next release. It will check a few more edge cases and hopefully be a little more robust to some of the more interesting…"

"Hi all,
I wrote this part of the code:
_rate_bf_target.x += _angle_bf_error.y * _ahrs.get_gyro().z;_rate_bf_target.y += -_angle_bf_error.x * _ahrs.get_gyro().z;
This takes care of the fact that when a copter is rotating in yaw, a zero roll error…"

"Hi Juraj,
I think the acro diagram on the post you point to is incorrectly labelled and should be Sport mode. This takes rate commands in the earth frame.
Now that I look at it, the diagram above should be labelled 3.1 not 2.9 too, so I have been…"

"Hi George Randall,
Sorry I didn't see this. I have had a look and two things look strange here. The first is that it looks like your alt hold altitude didn't reset to your current value before you took off again and also your autotune…"

"Thank you again for response!
I am talking about first controller = earth frame controller. On the left side of your PID diagram, this side is the same as by stabilize mode,except some constants according your…"

"Hi Juraj,
The angle error and rates are different when referenced in the earth frame compared to the body frame. We initially calculate them in the earth frame then translate them to the body frame before feeding them into the controllers."

"Thank you for response. So what you say, is that there is no difference if this earth frame controller is compensating yaw, pitch, roll according to earth frame or body frame?
When I think about it just like angles,just like numbers. The…"

"Hi Juraj,
They can be a series of rotations around the changing body frame axis ordered Yaw, Pitch, Roll. Or a series of rotations around the fixed earth frame axis ordered Roll, Pitch, Yaw. The two result in the same thing."

"Hi guys! I would love to understand the earth frame controller. There is still one thing which I can not understand properly.
I checked code and also all documentation which I could find. There is written for earth frame controller that…"

"Hi guys! I would love to understand the earth frame controller. There is still one thing which I can not understand properly.
I checked code and also all documentation which I could find. There is written for earth frame controller that…"

Profile Information

RF Engineer with a solid understanding of filtering and control loops.

Please tell us a bit about your UAV interest

Quads and gliders.

My quad has been a quick development to take some aerial photography on a 4wd trip along the Simpson desert.

I am on my second frame design that now folds up nice and tight and also carries the go pro effectively. It has pitch compensation through the ARM2 and 5.8GHz video feed back to some Fatshark goggles.

I am happy with the pids but I feel like loiter could be improved. Most of my tuning problems have come from the absence of the latest control loop descriptions on the wiki. But that goes with a community development like this. Maybe when I have time to go through the code I can draw up some new diagrams for the wiki.

I have broken 6 props, 5 on parts of my body an 1 on the ground. I had an esc cut out and tilt the quad into my legs on landing. I reset the esc's and forgot to reset the cut-out. I then had a mystery takeoff at my feet as I was downloading logs. I had plugged the battery in because I sometimes have trouble connecting when only powered by usb. Stupid mistakes....

All in all I am happy with my first attempt, especially as I really only spent about 4 days over the last 4 weeks working on this and it is my first quad attempt.

I would like to thank the DIY drones team for a fantastic job and I hope I can help in the future.

Leonardthall's Blog

I thought I would share the copter I hoped/hope to fly at ACV this year. I wanted to try to see what speeds I could get from a quad. I also thought it would be interesting to see what I could to with a 3d printer. I have access to a Makerbot 2x and I was also adding a heated bed to a friends printer.…

My motivation to get involved in the development team was to bring a good ACRO mode to ArduCopter. Three or four months ago Robert Lefebvre suggested that we could integrate the rate error and use it to correct the platform in the body frame. He went on to demonstrate this…

I have been thinking about the way we have implemented our throttle and the performance issues that we have observed. First of all I would like to say that I get great altitude hold. I can cruise around at 1 or 2 meters above the ground with no problems. It is only when I start to get…

Comment Wall (7 comments)

Thanks for your comment! Thats really interesting. Are you working in research or on applications? I my younger days I worked in the domain of the good old stripline technique for mw oscillators and amplifiers at the ETH Zurich and later on mw transmission systems for telephony and video for a swiss telecom operator. Also some years in mainly system aspects for high bitrate fiber transmission systems Now I am early retired due to restruction at this operator.

Is it possible for me to receive a copy of your Matlab / Simulink simulation software to get a feeling? I am not yet enough used to rebuild up your models including the quad in Matlab / Simulink.

By the way I attached the sonar sensor some 8 cm away from the center (see attached photo). Now the noise and spikes are reduced quite substantially. A further reduction is expected when connecting the APM 2 to the BEC I received from the DIY Drone shop. Best regards Jack

Another question concerning your Matlab/Simualtion sofware. Did you determine the quadrotor model i.e. inertia values by experiments? If yes, which way? I found recently indications that someone used a so called trifilar pendulum method (see Harris' Shock and Vibration Handbook).

With the new seperate BEC from the DiYDrone shop and placing the sonar sensor a few centimeters away from the electronic "center" the noise and observed spikes (when changing throttle) diminshed quite a lot. I am awaitung better times (without snow and rain) for a first fly outside for experiments and tuning.

Did you see already my last comment concerning receiving a copy of your matlab simulation program and determination of the drone i.e. inertia parameters and thrust?

Hi leonardthall, really thanks for that paper, I'll try to figure out how it works and try to use it fusing other sensors like Optical Flow and GPS or ACC. That filter is really a fantastic magic, i'll learn how to perform that magic by my self.

i know that this is a strange way to contact you but I was wondering if i could get some help with editing the ArduPilot's user code sections ?
if you email me off list at a.bazley@gmail.com you would rock.